The Present invention relates to stippling pattern stitching apparatus and sewing machine.
The stippling pattern is such a pattern as being depicted by a continuous line that is variously and complicatedly extended as is curved. The pattern is generally used for kilting stitches and the like.
The stippling pattern is generally stitched by manual operation by use of so called a free motion technique. Namely the stitching operation speed of sewing machine needle is adjusted by manipulation of a machine motor controller with manual adjustment of transporting amount of cloth while the feed dog is made ineffective as is moved to a lower position. However a special skill is required to stitch a proper stippling pattern because it is required that the cloth transporting amount and the stitching operation speed of sewing machine needle are simultaneously adjusted so that the pitch width of stitches may be maintained constant. It is, therefore, almost impossible for the machine users in general to stitch the stippling pattern at a large kilt cloth by use of a sewing machine.
Under such circumstances, it has been recently proposed to mechanically stitch the stippling pattern as shown in the document JP-A-20(2008)-136623 by way of example. The document discloses a technique to automatically produce the stippling pattern data.